Patients randomized to receive Lupron will receive a three month depot dose 3-6 weeks prior to the start date of the pre-transplant conditioning regimen. Patients assigned to receive palifermin will receive this drug at 60mcg/kg/day IV on three consecutive days, 24 hours apart with the last dose administered no less than 24 and no more than 48 hours prior to the start of cytoreduction. The preparative regimen to be used for transplants will consist of: hyperfractionated TBI administered in 11 doses over 4 days for a total of 1375 cGy, thiotepa 5 mg/kg/day IV x 2 days and cyclophosphamide with mesna prophylaxis 60 mg/kg/day IV x 2 days. All patients will receive ATG for two doses prior to transplant, except recipients of mismatched grafts (in the GVHD vector) will receive three doses. G-CSF mobilized CD34 PBSCs obtained from the HLA compatible donor will be infused on day 0. Patients assigned to receive palifermin will receive three additional daily doses of the drug, the first approximately 6 hours after the stem cell infusion on day 0, followed by two daily doses given at 24 hour intervals on d+1 and d+2. Patients assigned to receive Lupron will receive a further 3-month depot injection approximately 3 months (+/- one week) post the first dose. Supportive care will be administered as per the BMT Service guidelines. The conditioning regimen may be modified to allow an extra day during conditioning or prior to the graft infusion if required by donor and/or patient scheduling restrictions.